Vinyl chloride and vinylidene chloride polymers are known to be self-extinguishing and relatively more flame retardant than other polymers such as polyethylene, polypropylene and the like. However, a substantial amount of smoke may be produced upon exposure of vinyl chloride and vinylidene chloride polymers to a flame. The fact that a polymer has good flame retardant properties does not necessarily mean that it will have good smoke retardant properties, as is well known to those skilled in the art.
U.S. Pat. No. 4,053,452 teaches the use of combinations of (A) melamine molybdate or substituted melamine molybdate and (B) cobaltous carbonate (CoCO.sub.3) cobaltic oxide (Co.sub.2 O.sub.3), cobalt (II) acetylacetonate, and cobalt (III) acetylacetonate and hydrates thereof as smoke retardant systems in vinyl chloride and vinylidene chloride polymer compositions. The patent, further, discloses that cobaltic oxide, as the sole smoke retardant, imparts some degree of improvement in the smoke retardation properties of vinyl chloride and vinylidene chloride polymer compositions, although the degree of protection is not as high as when the combination is used.